Barite Galena Pyrite Quartz Rhodochrosite Sphalerite

Specimen Summary

Barite is a barium sulphate mineral that occurs in many different colours and crystal shapes. It occurs in a variety of sedimentary and metamorphic settings and often replaces other minerals or fossils. Despite its many forms, it is relatively easy to identify because of its heavy weight. In fact, its name comes from the Ancient Creek “barys”, meaning heavy. Examples of different forms of barite include golden yellow honeycomb barite and Desert Rose barite that has a flower-like appearance. Barite is also often found in hydrothermal veins with ores of antimony, copper, lead, manganese and silver. Barite is used to add weight to oil and gas drilling fluids to prevent blowouts, as well as in paints and automotive parts, ceramics, LED TVs and medical applications. Geologists can analyze the oxygen and sulphur isotopes in barite to investigate ancient seawater compositions.

Galena is the main ore mineral for lead. Because of its relatively low melting temperature, it can be easily smelted and has been used as a source of lead since ancient times. Galena has a cubic crystal system and can often be found as cubes or octahedra. Its shiny grey metallic luster and heavy, dense nature make it easy to identify. Galena often contains small amounts of silver, which add to its economic value.

Pyrite is a common iron sulphide mineral found in many different geological settings. It has a brassy-yellow metallic colour that has caused many people to mistake it for gold, giving it the name “Fool’s gold”. Pyrite and gold can be quite easily distinguished from one another: pyrite is less yellow and much lighter and harder than gold, which can be scratched with a pocket knife.  Pyrite often forms perfect cubes, which can grow to quite large sizes, because of its crystal structure. The word pyrite comes from the Greek word ‘pyr’ meaning fire, because it will spark if hit with other metal or stone objects.

Quartz is the second most abundant mineral on Earth, occurring in many different types of rocks. Although usually clear or milky white in colour, quartz can be found in a variety of colours because of impurities in the crystal structure. Pure quartz is made up of silicon and oxygen only, but atoms of other elements, like iron or titanium, often make their way into the quartz crystal structure. Some varieties of quartz, like purple amethyst, are considered to be semi-precious gemstones and have been used since ancient times to make jewellery and decorative objects.

Rhodochrosite is a manganese carbonate mineral that is usually bright pink or red in colour. Other elements like iron, magnesium or calcium can substitute for manganese, giving the mineral a more grey, yellow or brown colour. Rhodochrosite takes its name from Ancient Greek "rhodochros", meaning rose-coloured. Because of its distinct colour, it is rarely confused with other minerals. Rhodochrosite usually forms in metamorphic and sedimentary rocks, precipitating out of chemical solutions circulating through the rock. When precipitation occurs in several separate episodes, different layers form, each with a slightly different composition and colour, giving it a banded appearance. Rhodochrosite is mainly used in jewellery and is often found and mined from silver deposits. Well-developed rhombic crystals are very rare.

Sphalerite is the main ore mineral for zinc, and although relatively common, finding it in commercial amounts is somewhat rarer. The zinc will give the mineral a yellow or red hue, but iron can replace the zinc in the atomic structure, making the crystals black. Rarely, cobalt finds its way into the structure, and produces green crystals. Although sphalerite is a relatively soft mineral, it can be cut (faceted) into attractive gems, which are used for mineral displays.

This sample is from the Keystone mine on the west side of the Coldwater River, 6 km north of Coquihalla Lakes in southwestern BC.

The area was first staked in the early 1900s and developed in the 1930s. The mine was only active for a year, producing 81 tonnes of ore in 1955.

The mine’s main ore minerals can be seen in this sample: rhodochrosite, sphalerite and galena with small amounts of chalcopyrite. These occur with barite and quartz in narrow veins up to around 10 cm wide.

At Keystone, the veins are concentrated along a shear zone about 150 m wide, which is an area that has been deformed and faulted. The ore fluids traveled along the shear zone, eventually cooling and precipitating the minerals seen there. The banding seen in the sample suggests several pulses of fluids with slightly different compositions flowed through the rock to form the veins.

Specimen Data

 

The information listed below relates to the current holding location or collection that the sample is from, and whether the item is viewable at that location or is part of a private collection. Coordinates are given as guides, and we remind you that collecting specimens from these locations is not allowed. Caution is advised visiting such sites and Below BC assumes no responsibility for any injuries or trespassing charges that may occur as a result of the viewer entering these sites.

Collection Details

Original Collection:

Association for Mineral Exploration (AME)

Sub Collection:

-

Collection ID:

AME-506

Virtual Museum ID:

19-AME506

Accessibility:

Date Added to VM:

2018-02-08

Location Information

Sample Origin:

Coquihalla Lake, BC

Specific Site:

Keystone Mine

UTM Easting:

642437

UTM Northing:

5506377

Datum:

10 (NAD 83)

Coordinate Accuracy:

Approximate

Specimen Details

VM Category:

Mineral

Primary Features:

Barite Galena Pyrite Quartz Rhodochrosite Sphalerite

Primary Mineral Formula:

PbSpyrp, FeS2, SiO2, PbS, MnCO₃, (Zn,Fe)S

Primary Category:

sulphate sulphide oxide carbonate

Secondary Features:

Advanced Geological Information

 

The following section provides geological data relating to the specimen or the site it was collected from, when available. Information has been obtained from various sources including private and government datasets but may not be up to date. Any geological time periods or ages listed often relate to the primary geology of the area, and may not be the actual date of an event such as mineral formation.

Geological Formation:

Keystone Stock

Geological Period:

Early Tertiary

Stratigraphic Age:

33.9 to 66 Million Years Ago

Geological Belt:

Intermontane

Geological Terrane:

Plutonic Rocks

Minfile ID:

092HNW024

Minfile Link:

http://minfile.gov.bc.ca/Summary.aspx?minfilno=092HNW024

Site Details:

The Keystone mine is located on the west side of the Coldwater River, approximately 6 kilometres north of the Coquihalla Lakes. Base and precious metal mineralization were originally discovered at this locality in the early 1900's and underground development had taken place by 1936. The only production from the mine occurred in 1955, when 81 tonnes of ore were shipped for processing (Minister of Mines Annual Report 1955, page A48).

The geology of the upper Coldwater River area is characterized by Late Triassic Nicola Group metavolcanic and metasedimentary rocks derived from the emplacement of plutonic rocks assigned to the Late Jurassic and Early Cretaceous Eagle Plutonic Complex to the west. Along the Coldwater River, the Nicola Group comprises amphibolite, foliated diorite, mylonite and chlorite schist with minor marble in contact with gneissic granodiorite. A dioritic stock of Early Tertiary age has intruded these plutonic rocks west of this contact.

The Keystone mine is situated near the centre of the Early Tertiary quartz diorite (Keystone) stock, which has been estimated to be approximately 1300 by 2200 metres. The southern half of the stock is brecciated, as is the older granodiorite adjacent to it. The brecciation has been attributed to the subsequent emplacement of small stocks and dykes of porphyritic rhyolite. This event was apparently accompanied by pervasive alteration and the introduction of metallic mineralization.

In the area of the mine, rhodochrosite, sphalerite and hematite with galena and minor chalcopyrite and magnetite occur with or without quartz(-carbonate) as veins, veinlets and stringers in shears and brecciated zones. Erratically distributed gold and silver values reportedly occur with the quartz.

The dominant structure hosting this mineralization is a steeply dipping, north-northeast striking shear zone expressed, on the surface, by conspicuous rock alteration and manganese staining. This shear extends from the Stonewall adit (092HNW034)/Julie zone (092HNW023) on Mine Creek northeast past the Keystone mine, and attains widths in excess of 150 metres (diamond-drill hole 80-W2).

Three "vein zones" are known to be hosted along the structure. The No. 1 Vein zone, developed from two levels at the Keystone Mine, comprises quartz, calcite and rhodochrosite with pyrite, sphalerite, galena and rare tetrahedrite. It averages from 5 to 10 centimetres wide, but pinches and swells from a one-centimetre wide pyrite-gouge clay zone to a 30-centimetre wide massive pyrite-quartz vein with minor base metals. It also splits and branches where exposed on the lower level of the mine. A total strike length of approximately 275 metres has been explored, both in underground workings and drill holes.

Detailed sampling of the vein has produced erratic precious metal values. Silver values have ranged from better than 35 to over 754 grams per tonne. Gold values have been generally low. The best assay from the upper level has been one of 29.5 grams per tonne gold and 576.0 grams per tonne silver across a "very narrow" hangingwall vein (Assessment Report 19139). Values up to 5.07 grams per tonne gold and 275.7 grams per tonne silver have been obtained from samples from the upper level.

Two mineralized intersections averaging one metre in width were encountered in drill holes northeast of and below the mine workings, but precious metal values were very low. A second vein, which assayed 23.25 grams per tonne gold and 41.14 grams per ton silver across a 3.05-metre intercept, was discovered at depth further to the northeast (Assessment Report 19139). Veining intersected in a follow-up hole, however, did not contain significant precious metal values.

Additional Images